Sterile water repellent laminated sheet material

ABSTRACT

A STERILE WATER REPELLENT FIBROUS LAMINATED SHEET MATERIAL FOR SURGICAL DRAPES AND THE LIKE IS DISCLOSED. THE ADHESIVE USED TO BOND THE SHEETS TOGETHER HAS A SALINE EXTRACTION SURFACE TENSION GREATER THAN 55 DYNES/CM. AND THE FINISHED SHEET HAS A SALINE REPELLENCY OF GREATER THAN 24 HOURS.

United States Patent 3,575,794 STERILE WATER REPELLENT LAMINATED SHEET MATERIAL Thomas H. Shelley, East Brunswick, and George A.

Crowe, Jr., Plainfield, N.J., assignors to Johnson &

Johnson No Drawing. Filed Mar. 8, 1966, Ser. No. 532,598 Int. Cl. B3211 27/10 U.S. Cl. 161-250 3 Claims ABSTRACT OF THE DISCLOSURE A sterile water repellent fibrous laminated sheet material for surgical drapes and the like is disclosed. The adhesive used to bond the sheets together has a saline extraction surface tension greater than 55 dynes/cm. and the finished sheet has a saline repellency of greater than 24 hours.

This invention relates to water repellent laminated sheet materials and, in particular, to sterile water repellent laminated sheet materials of the type having a plurality of fibrous sheets adhesively bonded one to another.

Adhesively laminated fibrous sheet materials have been proposed in U.S. Pat. 2,900,980 to Harwood, U.S. Pat. 2,902,395 to Hirschy, and U.S. Pat. 3,072,511 to Harwood for making limited use disposable products for various purposes. It has been further proposed to render these fibrous laminated sheet materials water repellent by treating one or more of the sheets with a water repelling agent and to subsequently sterilize the same, the proposed treated fabric then being used for such products as surgical drapes and the like. However, independent of the type of repellent used and the amount of repellent used, after water repellent sheet materials of this type have been subjected to either steam or chemical sterilization, it is found that a water or saline solution will strike through the fabric relatively rapidly particularly in the areas where the various fibrous sheets are adhesively secured to each other.

It is, therefore, an object of this invention to provide a water repellent laminated sheet material comprising a plurality of fibrous sheets adhesively bonded one to another which is water repellent prior to sterilization and which will retain its repellency after sterilization.

According to this invention sterile, laminated sheet materials having a saline repellency of greater than 24 hours are provided. These materials comprise a plurality of fibrous sheets at least one of which has been treated with a water repellent, one of said sheets being adhesively bonded to a second of said sheets, the adhesive bonding the two sheets together being moisture resistant, nonfiowing at sterilizing temperatures and nontacky at room temperature, the laminated sheet material having a saline extraction surface tension which is greater than the surface tension of the surface of the repellent treated sheet. The inventive concept contemplates providing such a sheet material specifically by using an adhesive to bond the fibrous sheets together which has a saline extraction surface tension which is somewhat greater than the surface tension of the surface of the repellent treated sheet.

Saline repellency as used in this specification is measured in the following manner. A saline solution is prepared with 9 grams of sodium chloride per liter of distilled water. 600 millimeters of the saline solution is placed in a one quart mason jar. A piece of the chemically sterilized fabric is placed on the top of the jar and fastened in place with an O ring. The jar is inverted and placed on a fiat glass plate, the fluid head being about 4 inches. The time required for the saline solution to wet the glass plate is taken as the saline repellency of the fabric.

The saline extraction surface tension as used in this specification, is measured in the following manner. A 5" x 5" piece of the adhesively bonded fabric is placed in the bottom of a Petri dish and sterilized for 30 minutes at about 240 F. The sterilized fabric is then subjected to extraction by placing millimeters of the above described saline solution in the dish at room temperature for a period of about 15 hours. The Du Nouy tensiom eter surface tension of the solution after the extraction is taken as the saline extraction surface tension of the fabric. When measuring the saline extraction surface tension of the adhesive, the bottom of a Petri dish is coated with 10 grams of the adhesive mass. The adhesive is then baked in the dish to cure the same at 170 C. for about 3 minutes and is subsequently sterilized for 30 minutes at about 240 F. and the above described procedure again followed.

It has been surprisingly found that in order to provide a sterile repellent sheet material, the components of the sheet individually and in combination must have a saline extraction surface tension which is higher than the surface tension of the surface of the material and that it is the adhesive component of the conventional laminated sheet materials which does not meet this requirement.

The adhesives used to bond together the various sheets of a laminated sheet material which is to be sterilized must be nontacky at room temperatures, must remain nonflowing at sterilizing temperatures, must be resistant to the moisture encountered during sterilization, and should be of the type used in organisols and plastisols. For this reason, the adhesives generally used to bond together the various layers of sterilizable laminated sheet materials have been the polyvinyl acetates and polyvinyl chlorides. These materials characteristically have very low saline extraction surface tensions. Although polyvinyl acetate and polyvinyl chloride adhesives having high saline extraction surface tension have been available, they have not been considered to be desirable for use in laminated sheet materials because they are substantially more expensive and more difficult to handle because of their generally high viscosity, no one having previously recognized the critical nature of the saline extraction surface tension of each component of laminated sheet materials.

The adhesives used according to this invention must have a saline extraction surface tension somewhat above the surface tension of the surface of the fabric. This point is critical independent of the type of fibers in the sheet material and independent of the particular repellent which is used. Since fabrics treated with even the best repellents generally have a surface tension of no less than about 50 dynes/cm., and since the fibers and the repellent will lower the saline extraction surface tension slightly, the adhesives in general must have a saline extraction surface tension of greater than about dynes/ cm. and preferably above about dynes/cm. If a less efiicient repellent treatment is used, the adhesive must, of course, have even a higher saline extraction surface tension.

Although certain polyvinyl acetate and polyvinyl chloride adhesives have been found to be particularly suitable for use in a sterilizable laminated sheet material, any adhesive having the above described characteristics may be used according to this invention.

Several examples of the invention are given below only to illustrate the same and the invention should not be construed to be limited thereby.

EXAMPLE I A pressure sensitive adhesive composition is compounded consisting of 66.7 parts by weight of polyvinyl chloride, (sp. gr. 1.40; sp. viscosity at 20 C. of 0.54 centipoise, sold as Opalon 440 by Monsanto), 33.3 parts by weight of a di octyl phthalate plasticizer (mol. Wt.

390.57; sp. gr. 0.986; viscosity at 20 C. of 81.4 centipoises, sold as Flexol DOP by Union Carbide). The saline extraction surface tension of the adhesive is found to be 56.5 dynes/cm.

A laminated sheet material of the type consisting of a reinforcing scrim sandwiched between a plurality of thin paper sheets is formed by applying the adhesive to a 12 x 5 thread to the inch nylon reinforcing scrim having threads of 70 denier, at a dry coating weight of 50% of the scrim weight; disposing two sheets of cellulosic wad- 4 The resulting adhesive has a saline extraction surface tension of 50.0 dynes/cm. The fabric has a saline extraction surface tension of 45.3 dynes/ cm. and a saline repellency of 2 minutes.

The initial procedure of Example I is followed essentially as described except that the polyvinyl chloride resin is Geon 135 sold by B. F. Goodrich. The resulting adhesive has a saline extraction surface tension of 45.1 dynes/crn. The fabric has a saline extraction surface tension of 42.0 dynes/cm. and a saline repellency of 1 secl ding, each 4 mils thick and having a weight of 12.5 lbs. 0nd.

TABLE Laminate Adhesive Saline saline exsaline ex- Adhesive composition repellency traction 1 traction 1 Example:

I Opalon plus DOP 23 hours 50. 56. 5 II Opalon plus TOP 24 hours 54.4 59. 3 Control data Geon 120 X 203 plus DOP 19 minutes 46. 4 50. 5 QYNV-2 plus DOP 2 minutes- 45.3 50. 0 Geon 135 plus DOP 1 second 42. 0 48. 1

1 Surface tension dynes/cm.

per ream of 3,000 sq. ft., on each side of the scrim; and pressing the composite together so that the adhesive on the threads penetrates the entire first paper layer and a portion of the second paper layer on each side to integrally bond the various component layers of the laminate together. The adhesive is then cured by baking the laminate at 170 C. for 3 minutes.

The laminate is impregnated with a repellent which is 1.5 parts of a stearate chromium complex and 2.0 parts of a fluoro carbon in isopropanol to 5% by dry weight of the weight of the fabric. The surface tension of the fabric is found to be about 50 dynes/ cm.

The saline extraction surface tension and the saline repellency of the resultant fabric is measured as previously described. The saline extraction surface tension of the fabric is 50.0 dynes/cm. and its saline repellency is about 23 hours. The fabric thus produced is useful for fabricating surgical drapes, gowns and the like.

The above procedure is again followed essentially as described except that a di alkyl ketene dimer (mol. wt. of 520', melting point 43 C., sold as Aquapel 380 by Hercules Powder Co.) is used as the repellent. Similar results are obtained. This indicates that the critical saline extraction surface tension is not dependent on the type of re pellent which is used.

EXAMPLE II The initial procedure of Example I is followed essentially as described except that the adhesive plasticizer comprises 33.3 parts by weight of tri cresyl phosphate (mol. wt. 378; sp. gr. 1.16; viscosity at 20 C., 120 centi poises, sold as Flexol TCP by Union Carbide). The adhesive has a saline extraction surface tension of 59.3 dynes/cm. The fabric has a saline extraction surface tension of 54.4 dynes/ cm. and a saline repellency of greater than 1 day.

In addition to the examples of the invention given above, data is now presented to illustrate the critical nature of the saline extraction surface tension in providing a sterile repellent laminated sheet material.

The initial procedure of Example I is followed essentially as described except that the polyvinyl chloride resin used is Geon 120 X 203 sold by B. F. Goodrich. The resulting adhesive has a saline extraction surface tension of 50.5 dynes/crn. The fabric has a saline extraction surface tension of 46.4 dynes/crn. and a saline repellency of about 19 minutes.

The initial procedure of Example I is followed essentially as described except that the polyvinyl chloride resin is QYNV2 sold by Bakelite Division of Union Carbide.

The examples and data presented above indicate that if the saline extraction surface tension of a fabric having a surface tension of about 50 dynes/ cm. is below about 50 dynes/cm., strike-through of the saline solution occurs fairly rapidly but if the saline extraction surface tension is above 50 dynes/cm., strike-through does not occur for a substantial period of time. Since the nonadhesive components of such a fabric lower the saline surface tension of the fabric slightly, on the order of about 5 dynes/cm., the adhesive used to produce a fabric with a saline extraction surface tension of about 50 dynes/ cm. should have a saline extraction surface tension of greater than about 55 dynes/ cm.

Although several examples of the invention are given above, they are provided only for the purposes of illustration and the invention should be considered to be limited only by the following claims.

What is claimed is:

1. A sterile water repellent laminated sheet material comprising a plurality of thin paper sheets at least one of which has been treated with a water repellent, one of said sheets being adhesively bonded to another of said sheets, said adhesive being moisture resistant, non-softening at sterilizing temperatures, non-tacky at room temperatures and having a saline extraction surface tension which is greater than about 55 dynes/cm., said laminated sheet material having a saline extraction surface tension of greater than 50 dynes/cm. and having a saline repellency of greater than about 24 hours.

2. A sterile water repellent laminated sheet material of claim 1 in which said adhesive is chosen from the group consisting of the emulsion polymerized polyvinyl acetates and polyvinyl chlorides.

3. A sterile water repellent laminated sheet material of claim 2 in which said adhesive is polyvinyl chloride.

References Cited UNITED STATES PATENTS 2,410,884 11/1946 Lawrence l6l156 2,459,955 1/ 1949 Morrison et al. 161-VINYL 2,902,395 9/1959 Hirschy et al. 16157 3,072,511 1/ 1963 Harwood 161-57 3,087,848 4/1963 Rash 156280 MORRIS SUSSMAN, Primary Examiner US. Cl. X.R. 

